* Re: [PATCH v2] nbd: Fix memory leak in nbd_add_socket
@ 2020-06-20 12:05 Markus Elfring
2020-06-22 3:25 ` Zhengbin (OSKernel)
0 siblings, 1 reply; 3+ messages in thread
From: Markus Elfring @ 2020-06-20 12:05 UTC (permalink / raw)
To: Zheng Bin, linux-block
Cc: nbd, Navid Emamdoost, Navid Emamdoost, Kangjie Lu,
Stephen McCamant, Qiushi Wu, kernel-janitors, linux-kernel,
Jens Axboe, Josef Bacik, Tuomas Tynkkynen, Yi Zhang
> If we add first socket to nbd, config->socks is malloced but
> num_connections does not update(nsock's allocation fail), the memory
> is leaked. Cause in later nbd_config_put(), will only free config->socks
> when num_connections is not 0.
>
> Let nsock's allocation first to avoid this.
I suggest to improve this change description.
Can an other wording variant be nicer?
…
> +++ b/drivers/block/nbd.c
> @@ -1037,21 +1037,22 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
> return -EBUSY;
> }
>
> + nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);
Please use the following code variant.
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?id=4333a9b0b67bb4e8bcd91bdd80da80b0ec151162#n854
+ nsock = kzalloc(sizeof(*nsock), GFP_KERNEL);
…
> if (!socks) {
> sockfd_put(sock);
> + kfree(nsock);
> return -ENOMEM;
> }
Please take another software design possibility into account.
if (!socks) {
- sockfd_put(sock);
- return -ENOMEM;
+ kfree(nsock);
+ goto put_socket;
}
Regards,
Markus
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] nbd: Fix memory leak in nbd_add_socket
2020-06-20 12:05 [PATCH v2] nbd: Fix memory leak in nbd_add_socket Markus Elfring
@ 2020-06-22 3:25 ` Zhengbin (OSKernel)
2020-06-22 7:52 ` Markus Elfring
0 siblings, 1 reply; 3+ messages in thread
From: Zhengbin (OSKernel) @ 2020-06-22 3:25 UTC (permalink / raw)
To: Markus Elfring, linux-block
Cc: nbd, Navid Emamdoost, Navid Emamdoost, Kangjie Lu,
Stephen McCamant, Qiushi Wu, kernel-janitors, linux-kernel,
Jens Axboe, Josef Bacik, Tuomas Tynkkynen, Yi Zhang
On 2020/6/20 20:05, Markus Elfring wrote:
>> If we add first socket to nbd, config->socks is malloced but
>> num_connections does not update(nsock's allocation fail), the memory
>> is leaked. Cause in later nbd_config_put(), will only free config->socks
>> when num_connections is not 0.
>>
>> Let nsock's allocation first to avoid this.
> I suggest to improve this change description.
> Can an other wording variant be nicer?
em, how about this?
When adding first socket to nbd, if nsock's allocation fails, config->socks
is malloced but num_connections does not update, memory leak will
occur(Function
nbd_config_put will only free config->socks when num_connections is not 0).
>
>
> …
>> +++ b/drivers/block/nbd.c
>> @@ -1037,21 +1037,22 @@ static int nbd_add_socket(struct nbd_device *nbd, unsigned long arg,
>> return -EBUSY;
>> }
>>
>> + nsock = kzalloc(sizeof(struct nbd_sock), GFP_KERNEL);
> Please use the following code variant.
> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/coding-style.rst?idC33a9b0b67bb4e8bcd91bdd80da80b0ec151162#n854
>
> + nsock = kzalloc(sizeof(*nsock), GFP_KERNEL);
>
>
> …
>> if (!socks) {
>> sockfd_put(sock);
>> + kfree(nsock);
>> return -ENOMEM;
>> }
> Please take another software design possibility into account.
>
> if (!socks) {
> - sockfd_put(sock);
> - return -ENOMEM;
> + kfree(nsock);
> + goto put_socket;
> }
>
>
> Regards,
> Markus
>
> .
>
^ permalink raw reply [flat|nested] 3+ messages in thread
* Re: [PATCH v2] nbd: Fix memory leak in nbd_add_socket
2020-06-22 3:25 ` Zhengbin (OSKernel)
@ 2020-06-22 7:52 ` Markus Elfring
0 siblings, 0 replies; 3+ messages in thread
From: Markus Elfring @ 2020-06-22 7:52 UTC (permalink / raw)
To: Zheng Bin, linux-block
Cc: nbd, Aditya Pakki, Navid Emamdoost, Kangjie Lu, Stephen McCamant,
Qiushi Wu, kernel-janitors, linux-kernel, Jens Axboe,
Josef Bacik, Tuomas Tynkkynen, Yi Zhang
>> Can an other wording variant be nicer?
>
> em, how about this?
>
>
> When adding first socket to nbd,
How do you think about to replace abbreviations by terms?
> if nsock's allocation fails,
… failed,
> config->socks is malloced
The data structure member “config->socks” was reallocated.
> but num_connections does not update,
But the data structure member “config->num_connections” was not updated.
> memory leak will occur(Function
> nbd_config_put will only free config->socks when num_connections is not 0).
A memory leak will occur then because the function “nbd_config_put”
will free “config->socks” only when “num_connections” is not zero.
Would you like to add an imperative wording to the commit message?
https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/Documentation/process/submitting-patches.rst?id=625d3449788f85569096780592549d0340e9c0c7#n151
Regards,
Markus
^ permalink raw reply [flat|nested] 3+ messages in thread
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2020-06-20 12:05 [PATCH v2] nbd: Fix memory leak in nbd_add_socket Markus Elfring
2020-06-22 3:25 ` Zhengbin (OSKernel)
2020-06-22 7:52 ` Markus Elfring
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